1. Technical Field
This invention relates to a method and apparatus for delivering oxygen into an environment of interest, such as blood plasma. More particularly, the invention concerns a method and apparatus for systemic oxygenation of hypoxemic blood by intravenous injection of an aqueous suspension of oxygen in a carrier, such as water.
2. Description Of Background Art
Oxygen administration by ventilation, even at a high inspired oxygen tension, may be ineffective in potentially reversible respiratory insufficiency in a clinical setting. Such conditions include adult respiratory distress syndrome, acute pulmonary edema, foreign body aspiration, pulmonary embolism, and respiratory distress syndrome of infancy. The problem of how to treat such conditions is compounded by the pulmonary toxicity that may result from prolonged exposure to relatively high inspired oxygen tensions.
Currently, the only potentially viable medical approach for systemic oxygenation of patients calls for use of an IVOX catheter. In such devices, gas exchange occurs at the interface of a membrane of multiple small tubules and blood in the inferior vena cava. Although the potential utility of such devices has been demonstrated clinically in a small number of patients, the large size of the catheter (7-10 mm diameter) which is inserted in the femoral vein, and the large surface area presented by the tubules may result in venous thrombosis and pulmonary embolism.
In the medical field, safe and effective oxygenation of hypoxemic blood (by intravascular injection of oxygen foam or an oxygen-liberating material) has not previously been achieved. Obstruction of capillaries by surfactant-stabilized foam, inadequate mixing with blood, or liberation of toxic breakdown byproducts (including toxic oxygen moieties) of an oxygen precursor would typically occur.
Accordingly, it is an object of the present invention to provide a means for injection of oxygen into an hypoxemic medium without bubble formation or coalescence.
It is a further object of the present invention to make the size of any bubbles formed upon oxygenation so small that mixing can be achieved rapidly, whereby excessive bubble coalescence and adherence between large numbers of bubbles do not occur.